In a motor vehicle equipped with an automatic transmission, typically a shifter lever is pivotable over a series of positions representative of desired transmission gears such as, for example, park (P), reverse (R), neutral (N), drive (D), and low gear (M). The shifter lever is connected to the motor vehicle automatic transmission by a suitable mechanical and/or electronic operating linkage to effect actuation of the transmission to the selected gear when the shifter lever is moved to the transmission gear's representative position. A user-actuated detent assembly typically releasably secures the shifter lever in a desired position to prevent inadvertent movement to other positions but permit desired movement to other positions. The detent assembly can include a mechanical actuator which is manually operated by the user to release the detent assembly or an electronic actuator which is electrically operated to release the detent assembly. A shifter having an electrically actuated detent assembly to selectively permit movement of the shift lever between the gear positions is typically referred to as a shift-by-wire shifter.
While shift-by-wire shifter systems have many benefits, under some circumstances the operator may not be able to move the shifter lever in the event of a power outage or a system failure. It is desirable for the shift lever to be in the park position in the event of a power outage or a system failure but this may not be possible if the power outage or system failure occurs when the shift lever is in a gear position other than the park position. Accordingly, there is a need in the art for a shift-by-wire shifter system which defaults to the park position when a power outage or system failure occurs.